FR2904324A1 - METHOD FOR HYDROPROCESSING A GAS FUEL LOAD, HYDROTREATING REACTOR FOR CARRYING OUT SAID METHOD, AND CORRESPONDING HYDROREFINING UNIT - Google Patents

Abstract

It also relates to a hydrotreating reactor for implementing said process, and to a corresponding hydrorefining unit.

Description

METHOD FOR HYDROPROCESSING A GAS FUEL LOAD, HYDROTREATING REACTOR

  The invention relates to a process for the hydrotreatment of a diesel fuel feedstock, a hydrotreatment reactor for carrying out the said process, and a hydrorefining unit for carrying out the process. corresponding. Due to the stringency of emission standards for diesel engines, the specifications of diesel engines over the past two decades have evolved and are creating new constraints that have led to a change in the formulations of diesel fuel mixtures. Since January 2005, the specifications of diesel engines are as follows (French standard EN590): Density (at 15 C): 820-845 kg / m3 T95% (Distillation temperature of 95% of diesel): 360 C (maximum) Sulfur content: 50mg / kg (maximum) Engine cetane: 51 (minimum) Calculated cetane (ASTM D4737): 46 (minimum) Cloud point: <-5 C in winter, <+++ 5 C in summer. The bases sought are therefore light bases, sulfur-free, with high cetane number, and distilling completely before 360 C.

  The objectives are to further reduce the sulfur content to a value of less than 10mg / kg by 2009 and to increase the minimum value of the cetane engine. One solution for improving the cetane number is to add a pro-cetane additive. It is most often of alkyl nitrates which intervene in the elementary stages of oxidation before the auto-ignition of the mixture. They reduce the ignition time and increase the cetane number by 3 to 5 points depending on the amount added. However, they are all the less effective as the cetane number of origin is low.

  Another solution is to add to the mixture a substitute fuel, such as a biofuel, because the vegetable oil esters generally have a good cetane number.

As a result, European Directive 2003/30 / EC aims in particular to promote the use of biofuels. In transport, the European community has adopted a target of 5.75% of biocombustible fuel (ICP) for fuel in 2010.

That is, the amount of biofuel present in the mixture should provide 5.75% of the blend's PCI. Currently, the French government has introduced a tax: the TGAP (General Tax of Polluting Activities), which concerns fuels released for consumption on French territory. The 10 fuels subject to this tax are SP95, SP98 and Diesel Engine. The objective of this tax is to encourage the incorporation of biofuel of agricultural origin by gradually increasing the% PCI (Lower Calorific Value) from 1.75% in 2006 to 7.00% in 2010. This addition is made on the energy base and the organic origin of the 15 incorporated products. Thus, ETBE (ethyl tert.-butyl ether) has a reduced rate since it contains only 47% ethanol (of agricultural origin) and a CIL lower than gasoline. For motor diesel engines, the most commonly used biofuels are vegetable oil esters, such as rapeseed oil methyl ester (EMC). These motor gas oils are generally obtained by mixing the biofuel with diesel after treatment of the latter. These mixtures are often made by the distributors, just before the distribution of fuel.

The mixtures obtained from vegetable oil methyl esters have the advantage of a cetane conforming to the standard, but their density is much higher than the specification of the standard (greater than 800 kg / m3), which causes formulation difficulties at high incorporation rates. Ethyl esters of vegetable oils also lead to overly heavy mixtures. Biomass refining processes that have been developed to produce these biofuels are already known. Thus, US 4,992,605, US 5,705,722 and SE 520,633 disclose processes for hydrotreating triglycerides forming vegetable oils. The reactions used, however, are strongly exothermic. In order to limit the problems associated with this high exothermicity, it is necessary to recirculate up to 80% of the feedstock at the outlet of the hydrotreating reactor at the inlet thereof, hence the need to the realization of a new installation dedicated to this hydrotreatment process, and to oversize this unit with respect to the quantity of the load actually treated.

The Applicant has developed a hydrotreatment process for incorporating a maximum of biomass in a diesel fuel without substantial modification of the conventional hydrotreating unit and, in particular, without liquid effluent recycle device at the head. of reactor, while obtaining a superior quality finished product (density, cetane number, cloud point, stability). For this purpose, the invention relates to a process for the catalytic hydrotreatment of a feed of petroleum origin of diesel type in at least one fixed bed hydrotreating reactor, for the manufacture of diesel fuel, characterized in that incorporates vegetable oils and / or animal fats in said filler up to a level of about 30% by weight, the mixture of said filler and vegetable oils and / or animal fats being introduced into the reactor operating at a rate of passes without recycle liquid effluent at the reactor head. The catalytic hydrotreating process which is the subject of the present invention is capable of operating under particularly advantageous conditions when said feedstock to be treated is introduced into the reactor with a level of vegetable oils and / or animal fats of 2.5 to 25. % by mass. In fact, according to the invention, it is not necessary to make any major modifications to petrol hydrotreating units when relatively small amounts of biomass are incorporated in the latter (for example at less than 10% incorporation), since the high exothermicity of the hydrotreatment of the triglycerides of the biomass is controlled by the presence of the diesel fuel charge. However, as soon as the rate of incorporation of biomass in the feed to be hydrotreated passes above such a value, it is still possible to use a conventional hydrotreating unit without major modification, and in particular without recycle of liquid effluent. at the reactor head, by adapting the conditions in a manner known per se. According to particular features of the invention: the feed of petroleum origin of diesel type is chosen from diesel type cuts from the direct distillation (or straightrun (SR) according to the English name) of a crude oil diesel-type cuts resulting from different conversion processes, and in particular those resulting from catalytic cracking and visbreaking. the vegetable oils are chosen from palm oil, soybean oil, rapeseed oil, sunflower oil, preferably palm oil, or a mixture of two or more of these oils. A quantity of hydrogen introduced into the reactor is used to treat the feedstock from 100 to 500 Normoliters of H2 per liter of feed, preferably from 120 to 450 Normoliters of H2 per liter of feedstock. the charge is treated at a temperature of 320 to 420 ° C., preferably 340 ° to 400 ° C., and more preferably 350 ° to 370 ° C., the batch is treated at a pressure of 25 to 150 bar, preferably 30 to 70 bars. the charge is treated on at least one catalytic bed in the reactor, the catalytic bed containing at least one catalyst based on metal oxides chosen from NiMo, CoMo, NiW, PtPd oxides, or a mixture of two or more of these. Advantageously, especially when the level of vegetable oils and / or animal fats is high, the filler is treated with at least one catalytic bed containing at least part of a catalyst based on nickel oxides. The catalytic beds containing NiW oxides have the advantage of catalysing the isomerization reactions, which can make it possible to improve, that is to say reduce, the cloud point of the finished product. In particular, in the case of a diesel fuel having a high cloud point, a catalyst bed containing NiW, and preferably NiW oxides on amorphous silica alumina, by promoting the isomerization reactions, will allow to reduce very clearly the cloud point of the finished product.

Catalytic beds containing NiMo oxide catalysts have a high hydrogenating and hydrodeoxygenating effect on triglycerides.

It is also particularly advantageous to treat the feedstock by means of several successive catalyst beds, with, for example, a first bed containing NiMo oxides to improve the hydrogenation of the triglycerides of the feed and / or or NiW oxides for catalyzing the isomerization reactions, and the following catalyst bed (s) containing CoMo catalysts which exhibit good hydrodesulfurization performance at low hydrogen pressure (the hydrogen having been partially consumed by hydrogenation in the presence of the NiMo catalyst).

The proportions of the different catalysts will be determined according to the reactions that one wishes to promote. In a conventional hydrotreating unit, gases that will be reinjected into the reactor after passing through a treatment system are separated from the effluent leaving the reactor. These gases, referred to as recycle gases, essentially contain hydrogen. When the level of vegetable oils and / or animal fats is high, the hydrotreating of a diesel fuel mixed with these vegetable oils and / or animal fats leads to the formation of carbon monoxide CO which will be found in this gas recycle.

In a particularly advantageous variant of the process comprising a treatment of recycle gas resulting from the hydrotreatment of the feedstock before its reinjection into the reactor, an additional treatment is carried out during which the carbon monoxide present in said recycle gas is treated. and separating it from said recycle gas prior to reinjection into the reactor. It is thus possible not to reinject the carbon monoxide into the reactor and not to risk inhibiting the catalyst. The treatment and separation of carbon monoxide can be achieved by introducing into the recycle gas treatment system a carbon monoxide treatment and separation device. In particular, it is possible to use CO conversion equipment (called CO shifts by specialists) such as those generally provided by hydrogen unit manufacturers. Such CO treatment can be carried out when the CO content of the recycle gases reaches a predetermined value. Advantageously, a treatment is also carried out in which the carbon dioxide present in said recycle gas 2904324 6 is treated and separated from said recycle gas before being reinjected into the reactor. This treatment is for example carried out by passing the recycle gas into an amine absorber. Another particularly advantageous way of using the invention, and here again as soon as the level of vegetable oils and / or animal fats is high, is to compensate for the exothermicity which necessarily results from the addition of these oils. Thus, advantageously, the exothermicity of the hydrotreatment of the feed is controlled by means of thermal control systems. In a conventional hydrotreating unit, it is for example an improvement of the liquid / gas distribution, quench gaseous or liquid effluents (that is to say the supply of cold gases or liquids in the reactor), for distributing the catalyst volume over several catalytic beds, for preheating the feedstock at the inlet of the reactor, in particular by acting on the furnace and / or the heat exchangers situated upstream of the reactor, bypass lines, etc., to lower the temperature at the reactor inlet. The invention also relates to a catalytic hydrotreatment reactor 20 for a feed of petroleum origin of diesel type for carrying out the process according to the invention, characterized in that it comprises at least one catalytic bed containing at least one a catalyst based on metal oxides selected from NiMo, CoMo, NiW, PtPd oxides, or a mixture of two or more thereof.

Advantageously, the reactor comprises at least one catalytic bed containing a catalyst based on nickel oxide. The invention also relates to a hydrorefining unit comprising at least one catalytic hydrotreating reactor of a diesel-type feedstock according to the invention.

It also relates to a hydrorefining unit comprising at least one catalytic hydrotreating reactor of a fuel of petroleum origin of diesel type and a separator separating the liquid and vapor phases from the effluent leaving the reactor, characterized in that it comprises, downstream of the separator, a unit for treating and separating the carbon monoxide present in the vapor phase of the effluent for carrying out the process according to the invention.

Advantageously, the unit comprises, downstream of the separator, a carbon dioxide treatment and separation unit present in the vapor phase of the effluent for carrying out the process according to the invention.

The vegetable or animal oils used according to the invention are mainly composed of triglycerides of fatty acids (> 90% by weight), the chain lengths depending on the nature of the oil used.

The vegetable oils may in particular be palm oil, soybean oil, rapeseed oil, sunflower oil, or a mixture of two or more of these oils. These oils will produce substantially C15 to C18 paraffins. Palm oil is therefore particularly preferred because it is one of the oils with the shortest carbon chains, with nearly 50% C16. As palm oil is one of the most saturated, its hydrotreatment requires a lesser amount of hydrogen compared to other oils. In addition, the thermal stability of the palm oil limits the fouling of the heat exchangers located upstream of the reactor in a conventional hydrorefining unit. Palm oil also has the advantage of having its profile centered on that of the diesel fuel, which limits the disruption of the latter, to be economical, and to be little used for human food.

As animal fats, for example, fish fat can be used. A particularly advantageous way of using the invention is therefore preferably to use palm oil or any other vegetable or animal oil capable of producing, by hydrotreating, a maximum of C15 to C18 paraffins, preferably C15 or C16, so as to induce a significant increase in the cetane number of the charges produced while reducing the density as much as possible, and to better value bases with low cetane number and high density, such as LCO (Light Cycle 35 Oil) which is characterized by a high density and a very low cetane number, and gas oils derived from acidic crudes which exhibit excellent cold properties but have the characteristics of having a high density and a low cetane. The invention is now described with reference to the accompanying drawings, which are non-limiting, in which: FIG. 1 is a simplified diagram of a hydrotreating unit 1. conventional diesel fuel type charge; FIG. 2 is a simplified diagram of a separation section of a conventional hydrotreating unit; 3 represents the distribution of normal paraffins nCx in the effluents, the number x being on the abscissa and the number n on the ordinate. FIG. 1 represents a simplified diagram of a unit 1 for conventional hydrotreating of a diesel fuel charge.

This unit 1 comprises a reactor 2 into which the charge to be treated is introduced by means of a line 3. This reactor contains one or more beds of hydrorefining catalysts. A line 4 recovers the effluent leaving the reactor 2 and leads it to a separation section 5.

A heat exchanger 6 is placed downstream of the reactor on line 4 in order to heat the charge flowing in line 3, upstream of the reactor. Upstream of this heat exchanger 6, a line 7, connected on line 3, provides the charge to be treated with a gas rich in H2.

Downstream of the heat exchanger 6, and upstream of the reactor 2, the charge mixed with the H2-rich gas flowing in line 3 is heated by a furnace 8. Thus, the charge is mixed with the hydrogen-rich gas, and then brought to the reaction temperature by the heat exchanger 6 and the furnace 8 before entering the reactor 2. It then passes into the reactor 2, in the vapor state if it is a section light, in liquid-vapor mixture if it is a heavy cut. At the outlet of the reactor, the mixture obtained is cooled and then separated in the separation section 5, which makes it possible to obtain: a gas G acid rich in H 2 S, a part of which is reinjected into the gas rich in mixed H2 to the load, by means of a line 9, light products L which result from the decomposition of the impurities. The elimination of sulfur, nitrogen, ... leads indeed to a destruction of many molecules and the production of lighter fractions, 5 - a hydrorefined product H of the same volatility as the load but with improved characteristics. Typically, the effluent leaving the reactor 2 is cooled and partially condensed, then enters the separation section 5. Such a separation section 5 generally comprises (FIG. 2): a first high pressure separating flask (from the order of 55 bars) which makes it possible to separate from the effluent a gas G (hydrogen-rich H21, which gas can be recycled), a second low-pressure separator balloon (10 bar) which separates the liquid and vapor phases. obtained by expansion of the liquid from the high pressure flask G (H2, L, H2S) gas obtained mainly contains hydrogen, light hydrocarbons and much of the hydrogen sulfide which has formed in the reactor A steam stripper 12 whose function is to remove light hydrocarbons L and residual H2S from the treated feedstock The hydrorefined product H is withdrawn at the bottom of this stripper, a vacuum dryer 13 allowing el iminating water solubilized by the hot hydrorefined product in the stripper. According to the invention, in a reactor forming part of a hydrotreatment unit, such as the hydrodesulfurization unit of the type described above, a mixture of a diesel fuel type charge and up to 30% by weight, preferably from 2.5 to 25% by weight of vegetable oils and / or animal fats. The hydrogen cover, that is to say the amount of hydrogen mixed with the feedstock is 100 to 500 Nl / l, preferably 120 to 450 Nl / l.

The temperature of the average reaction charge is 320 ° C. to 420 ° C., preferably 340 ° C. to 400 ° C., and preferably 350 ° C. to 370 ° C.

The pressure inside the reactor is 20 to 150 bar, preferably 30 to 70 bar. Preferably, a catalytic hydrotreating unit according to the invention also comprises a unit 14 for treating and separating the carbon monoxide produced in the reactor and separated in the separation section 5 of the effluent. Preferably, this treatment and separation unit is a conversion unit which converts CO to another compound which can be easily removed, such as for example carbon dioxide. This is for example a conversion unit of carbon monoxide to carbon dioxide according to the reaction: CO + H2O + CO2 + H2 The resulting carbon dioxide can then be easily removed, for example, by washing to the amines, while the hydrogen produced can be recovered for reinjection into the reactor or mixed with the hydrogen-rich gas mixed with the feedstock. Such a CO unit 14, known per se, is positioned to treat the gas phase separated by the separation section 5. In a separation section 5 comprising high (10) and low (11) separator flasks pressure as shown in Figure 2, this unit 14 will therefore preferably placed at the outlet of the gas separated by the high pressure separator (11).

The temperature at the outlet of this flask is of the order of 40.degree. C., and, depending on the nature of the catalyst used, the CO conversion temperature can reach 350.degree. C. It may then be necessary to heat the incoming process gas. in this conversion unit. Preferably, a catalyst will be selected which does not require heating of the gas. The CO conversion unit 14 will preferably be placed on a bypass line, so that CO conversion is only performed when the CO content of the gas exceeds a predetermined threshold.

Depending on the amounts of CO, there will be used for example: a low temperature conversion unit (usually called L7 'Shift), operating at a temperature of 2904324 11 190-220 C, for a CO content of less than 5000 ppm by volume a medium temperature conversion unit (usually called MT Shift), operating at a temperature of 220-270 ° C, for a CO content of 10,000 to 20000 ppm by volume, and a high temperature conversion unit (usually called HT Shift), operating at a temperature of 320-350 ° C. for a CO content of greater than 3% by volume.

This conversion unit 14 may be coupled to a CO2 treatment and separation unit, not shown, and known per se. EXAMPLES Three feeds based on diesel and vegetable oils were treated in a hydrodesulfurization pilot unit. The diesel fuel feed was treated without incorporation of vegetable oils in Example 1, which serves as a reference, and with 5%, then 10% and 20% by weight of palm oil in Examples 2, 3, and 4 respectively.

The experimental conditions are detailed below. Installation The method according to the invention was tested on a pilot unit comprising a reactor operating in the upflow mode of the liquid and gas streams: this reactor has a diameter of a few centimeters in diameter. A heater placed upstream of the reactor makes it possible to heat the charge to be treated before entering the reactor. 30 - The pilot unit does not have a recycle gas and the load is treated in a single pass, that is to say in Ounce according to the specialists. - The purity of the hydrogen injected into the pilot is 100%. The temperature profile of the reactor is constant, the reactor operating in isothermal mode. A nitrogen stripper section is present at the outlet of the reactor in order to eliminate the H2S, NH3 and H2O gases, in the case where these compounds are present in the effluent. The reactor comprises seven catalyst beds containing a porous alumina catalyst on which nickel and molybdenum oxides are deposited. This catalyst is in the form of extrudates 1 to 2 mm in diameter of quadrilobe shape. - The loading density is 950 kg / m3 of catalyst loaded into the unit.

Test Charge A low sulfur diesel fuel was used in the examples, with palm oil being of food grade. The characteristics of the diesel fuel and palm oil load are reported in Tables 1 and 2 respectively. Table 1: Characteristics of the Diesel Fuel Load Density at 15 C 0.8433 Sulfur Content (ppm) 1260 Basic Nitrogen Content (ppm) 20 Cloud Point ("C") -4 Pour Point (C) - 6 Index Cetane measured 56 Distillation temperature 5% 245.1 20% 260.3 50% 284.9 80% 314.3 95% 347.6 of gas oil (C, ASTM 86) Bromine number mg Br / 100g) 621 Content Polyaromatics (% in 8.2 weight) Total aromatics content (% 22.2 in weight 2904324 13 Table 2: Characteristics of palm oil Density at 15 C (calculated) 0.8956 Acid composition 12: 0 0.2 (percentages by weight) 14: 0 1.1 Lauric acid 16: 0 45.7 Myristic acid 16: 1 0.2 Palmitic acid 17: 0 0.1 Palmitoleic acid 17: 1 <0.1 Margaric acid 18 : 0 4.3 Stearic acid 18: 1 37.7 Oleic acid 18: 2 9.8 Linoleic acid 18: 30, 2 Linolenic acid 20: 0 0.4 Arachidic acid 20: 1 0.1 Gondoic acid 0.7 GPC: <0.1 Free fatty acids 7.1 Monoglycerides 92.0 Diglycerides 0.2 Triglyceri Not identified Elemental content (ppm) 0.5 Phosphorus Calcium <0.2 Copper <0.08 Iron 0.04 Magnesium <0.02 Sodium <0.1 Table 3 shows the density and sulfur content of the fillers Examples 1 to 4. The density of the filler increases with the proportion of vegetable oil incorporated.

Table 3: Sulfur and Density of Examples 1 to 4 Density at 15 C Sulfur Content GPC (ppm) (triglycerides) (wt%) Example 1: 0.8433 1260 0 Example 2: 0.8458 1190 5 Example 3: 0.8499 1090 10.0 Example 4: 0.8567 1040 20.0 Coverage of H2 Two blankets of hydrogen H 2 (i.e., the amount of 5 normoliters of hydrogen per liter load) were studied: 130 and 225 Nl / l. It is customary to fix the hydrogen blanket at 3 times the hydrogen consumption of the treated feedstock at the reactor inlet. The hydrogen blanket of 225 Nl / l is slightly greater than three times the hydrogen consumption of the feedstock treated at the reactor inlet with an addition of 10% by weight of palm oil. The hydrogen cover of 130 Nl / l corresponds to 3 times the hydrogen consumption of a diesel fuel without palm oil.

Operational conditions The operating conditions of the reactor were calibrated on a reference point determined beforehand on the reference diesel fuel. The pressure is 40 bar and the average treatment temperature is 340 C. This temperature makes it possible to ensure a sulfur content of less than 10 ppm from the reference gas oil treated here. In order not to have thermal cracking of the triglyceride molecules upstream of the reactor, the temperature of the preheater is maintained at a lower temperature than usual: 320.degree. C. It is the first catalytic bed which provides the additional heating of load. Table 4 (Operating conditions of the pilot unit) summarizes the operating conditions of the pilot unit used: Table 4: Operating conditions Total pressure (bar) 40 H2 / HC (N1 / 1) 130 and 225 VVH ( h 1) 1.0 Preheater temperature (C) 320 Reactor temperature (C) 340-350 When changing the load, the operating conditions are kept constant. The possible variation of the sulfur content due to the oil supply and / or the decrease of the hydrogen cover is measured. In addition, the total conversion of triglycerides is confirmed by GPC (gas chromatography). Subsequently, the reactor temperature can be adjusted to recover the initial sulfur content (<10 ppm). Product quality The incorporation of vegetable oil in charge of a hydrodesulfurization unit has the consequence of adding normal paraffins in the final product. Table 5 groups the results of a detailed analysis of the effluents obtained for the first 3 examples and a partial analysis for Example 4. Table 5 demonstrates that: The cold properties of the products obtained are relatively stable. Indeed, the cloud point increases from less than 1 C to 10% by weight of incorporation of palm oil and the TLF (Filtration Limit Temperature) of the order of 2 C. - The cetane engine, meanwhile , increases substantially: +2.2 for the cetane engine and +2.8 for the cetane calculated at 10% by weight of palm oil. This increase is very interesting for gas oils requiring pro-cetane additive to meet the specification. Since the products of the reaction of triglycerides all distillate before 360 ° C., the criterion T95 (temperature at which 95% of the product has distilled) varies favorably over this specification: -3.4 ° C. at 5% by weight of vegetable oil. Thus, the characteristics of the products obtained are favorably affected by the incorporation of vegetable oils in charge of a hydrodesulfurization unit. Table 5: Characteristics of the effluents of Examples 1 to 4 Example 1 2 3 4 Cover H2 / HC (Nl / l) 225 225 130 225 130 225 130 Temp. Reactor (C) 340 340 340 340 340 340 340 Density at 15 C 0.8382 Li 0.8346 0.8352 0.8321 0.833 0.827 0.828 Sulfur (ppm) 15.2 8.6 15.0 4.7 14.0 5.0 16.0 Cloud Point (C) -5.0 -4.6 -4.7 -4.3 -4.1 -2.5 -2.2 TLF (C) -9 -10 -9 -9 -7 - - Motor cetane number 56.2 56.7 57.8 58, 4 59.2 59.4 Calculated cetane number 57.8: 59.5 59 61 60.6 - - Normal paraffin 2,32 2 , 2.26 2.16 2.11 1.97 2.04 (wt%) C14 C15 2.68 3.13 3.23 3.99 4.21 5.94 6.43 C16 2.51 3 , 61 3.54 4.37 4.17 5.31 4.76 C17 2.34 2.80 2.91 3.86 4.13 6.29 6.63 C18 1.98 3.08 2.97 3 , 88 3.67 5.15 4.5 C19 1.56 I 1.48 1.48 1.40 1.42 1.38 1.32 GPC (triglycerides) (% <0.05 <0.05 <0 0.5 <0.05 <0.05 <0.05 wt.) Distillation temperature (C, ASTM D86) 5% (% distilled) 245.9 244.7 245.8 248.6 250.5 20 % 260.2 259.9 259.4 261.7 262.0 50% 281.7 281.9 281.2 282.2 282.0 80% 310.9 310.2 309.1 308.1 308.8 95% _ 346.4 L 342.9 343.0 340.9 342.5 2904324 17 Yield in normal paraffins Table 2 indicates that the oil of p alme is composed of 99% wt of glycerides. The C16 and C18 chains represent 98% of the acids contained in the oil. The hydrogenation of these glycerides should preferably lead to the formation of paraffinic chains of the same length nC 16 and nC 18. Figure 3 shows the distribution of normal paraffins in the effluents of Examples 1 to 3. The addition of oil palm in charge of the hydrotreatment leads to a significant increase in the normal paraffins between C15 and C18. The formation of odd-length chains is due to decarboxylation or decarbonylation (decarb-) during the hydrotreatment of the acid. This parasitic reaction leads to the emission of carbon monoxide (CO) and carbon dioxide (CO2) in place of water (H2O). In addition, methanation of CO leads to the formation of CH4. As can be seen in FIG. 3, it is interesting to note that decarb- increases by decreasing the hydrogen coverage and by increasing the incorporation rate of the oil. An increase of 12% by weight of decarb is observed between 5 wt.% And 10 wt.% Of palm oil. As previously described, the decarboxylation / decarbonylation causes the emission of CO gas, CO2 decreasing the partial pressure of hydrogen. Moreover, in addition to safety concerns on humans, CO is a reversible inhibitor of catalyst desulfurizing activity. The levels of CO and CO2 present in the gases were measured in the case of 10% by weight of palm oil incorporation (Example 3). It has been found that when the hydrogen coverage is lower (130N / 1, which corresponds to 1.8 times the estimated hydrogen consumption), more paraffinic chains are produced and thus more paraffinic chains are produced. C 1 gas (sum of CO, CO2, CH4). On the other hand, the concentration of CO is less important in the case of low hydrogen cover to favor the production of CO2.

These results are collated in Table 6.

Table 6: CO and CO contents of qaz at the outlet of the pilot unit Charge Example 1 Example 2 H2 / HC 225 Nl / l 225N1 / 1 130N1 / 1% mol% wt% mol% wt% mol% wt CO 0 , 00 0.00 0.64 4.03 0.86 3.85 CO2 0.00 0.00 0.88 8.70 2.37 16.57 CH4 0.06 0.53 0.34 1.22 0 1.77 A 100/0 feed of palm oil corresponds in exothermic terms to about 40% LCO feed, or 20% visbreaking gas oil + 10% LCO. This exothermicity can be controlled with little or no operational changes of a conventional unit. 20% of palm oil corresponds in exothermic terms to about 60% LCO, or about 40% visbreaking gas oil at the reactor head. The exotherinicity is then controlled by varying the number of catalytic beds, using adapted quenchs, ....

Claims (17)

  1. Process for the catalytic hydrotreatment of a feed of petroleum origin of diesel type in at least one fixed bed hydrotreating reactor, for the manufacture of diesel fuel, characterized in that vegetable oils are incorporated in said feedstock and / or animal fats up to a level of approximately 30% by weight, the mixture of said filler and vegetable oils and / or animal fats being introduced into the reactor operating in a pass, without recycle of liquid effluent at the reactor head.   2. Catalytic hydrotreating process according to claim 1, characterized in that the level of vegetable oils and / or animal fats is 2.5 to 25% by weight.   3. Process for catalytic hydrotreatment according to claim 1 or 2, wherein the charge of petroleum origin of diesel type is selected from the diesel coupes from the direct distillation of a crude oil, the diesel cuts from different processes of conversion, in particular, those resulting from catalytic cracking and visbreaking.   4. Catalytic hydrotreatment process according to one of claims 1 to 3, wherein the vegetable oils are selected from palm oil, soybean oil, rapeseed oil, sunflower oil, preferably palm oil, or a mixture of two or more of these oils.   5. Process for catalytic hydrotreatment according to one of claims 1 to 4, wherein the amount of hydrogen introduced into the reactor to treat the load is 100 to 500 Normoliters of H2 per liter of filler, preferably 120 to 450 Normoliters of H2 per liter of charge.   6. Catalytic hydrotreating process according to one of claims 1 to 5, wherein the filler is treated at a temperature of 320 to 420 C, preferably from 340 to 400 C.   7. Catalytic hydrotreating process according to one of claims 1 to 6, wherein the filler is treated at a pressure of 25 to 150 bar, preferably 30 to 70 bar.   8. Process for catalytic hydrotreatment according to one of claims 1 to 7, wherein the feedstock passes through at least one catalyst bed in the reactor, the catalyst bed containing at least one catalyst based on metal oxides chosen from NiMo, CoMo, NiW, PtPd oxides, or a mixture of two or more thereof.   9. Process for catalytic hydrotreatment according to one of claims 1 to 8, wherein the feedstock introduced into the reactor is treated on at least one catalytic bed containing at least partly a catalyst based on nickel oxides.   10. Catalytic hydrotreatment process according to one of claims 1 to 9 comprising a treatment of recycle gas from the hydrotreatment of the feedstock before its reinjection into the reactor, in which an additional treatment is carried out during which treating the carbon monoxide present in said recycle gas and separating it from said recycle gas prior to re-injection into the reactor.   The catalytic hydrotreatment process according to claim 10, wherein a treatment is further carried out during which the carbon dioxide present in said recycle gas is treated and separated from said recycle gas before being reinjected into the reactor. .   The catalytic hydrotreatment process according to one of claims 1 to 11, wherein the exothermicity of hydrotreatment of the feed is controlled by means of thermal control systems.   13. Reactor for catalytic hydrotreating of a petroleum diesel type feedstock for carrying out the process according to one of the preceding claims, characterized in that it comprises at least one catalytic bed containing at least one catalyst based on metal oxides selected from NiMo, CoMo, NiW, PtPd oxides, or a mixture of two or more thereof.   14. catalytic hydrotreating reactor according to claim 13, characterized in that it comprises at least one catalytic bed 30 containing a catalyst based on nickel oxide.   15. Hydrorefining unit comprising at least one catalytic hydrotreating reactor of a petroleum type diesel feedstock according to claim 13 or 14.   16. A hydrorefining unit comprising at least one catalytic hydrotreating reactor of a charge of petroleum origin of diesel type and a separator separating the liquid and vapor phases from the effluent leaving the reactor, characterized in that it comprises, downstream of the separator, a carbon monoxide treatment and separation unit present in the vapor phase of the effluent for carrying out the process according to claim 10.   17. The hydrorefining unit according to claim 16, comprising, downstream of the separator, a unit for treating and separating carbon dioxide present in the vapor phase of the effluent for carrying out the process according to claim 11.